The present invention broadly relates to liquid fuel supply systems and, more specifically, pertains to a new and improved construction of a liquid fuel preheater or preheater device.
Generally speaking, the device of the present invention for preheating liquids, for instance liquid fuels, is, in its more particular aspects, a preheater having a heat-exchanger adapted for the liquid to be heated to flow therethrough and comprising a surface or superficial heating chamber which is closed off on at least one side by a heat-conductive wall, and having a surface heat source which acts on this wall.
In a preheater of this general kind known from the German Patent Publication No. 3,202,533, published Aug. 4, 1983, a heat source in the form of an incandescent lamp is arranged close to a heat-conducting heating wall of a superficial heating chamber. A reflector serves to concentrate the radiation from the lamp onto the heating wall. The heating wall may, additionally, be blackened to enhance heat absorption. As a result of the liquid being conducted as a stream along a superficial or surface-like heating wall, a particularly effective heating of the liquid is achieved and by repeated variation of the cross-sectional shape of the liquid stream good intermixture of the liquid is achieved. However, widening or expansion of the layer of liquid onto a disc-shaped heating chamber, as required by a punctiform heat source, in turn entails difficulties of flow, especially at the edge zones. Moreover, with the use of such a heating element, the preheater is spatially enlarged to a significant extent.
Another preheater, especially for Diesel fuel, known from the U.S. Pat. No. 4,349,001, granted Sept. 14, 1982, provides for a flat or plate-shaped heat-exchanger in which the liquid, flowing in and out through pipes, is distributed superficially and the heating surfaces of a ribbon-shaped heating chamber thereof are formed by longitudinally-ribbed partition walls. The heat source is a heating liquid medium which flows externally along the partition walls. In this preheater, too, a flow pattern uniform over the stream width of the liquid that is to be heated is not possible and also satisfactory heat transfer cannot be achieved. Furthermore, the heating liquid medium entails the provision of an additional housing and connections and the expenditure associated therewith.